Carrier sense multiple access/ collision avoidance – visualisation teaching tool (CSMA/CA-VTT)

Jameson Mbale

University of Namibia

Email: mbalej@yahoo.com

Accepted 03 September, 2012

Abstract

A Carrier-Sense Multiple-Access/Collision Avoidance (CSMA/CA) was a telecommunication protocol that first listened before sending a frame through a medium in order to avoid collision among heterogeneous sites across a network. To teach such a mechanism to students in the traditional format, especially to the ones from the Sub-Saharan region was a difficult to visualize such a concept. In view of that, Carrier-Sense Multiple-Access/Collision Avoidance – Visualisation Teaching Tool (CSMA/CA-VTT) was envisaged to demonstrate step-by-step the phenomenon of “listen-before-talk”, the mechanism of Inter Frame Spacing (IFS) and Backoff Timer (BOT) decremented generated random time to zero (0) to give one station high priority to send a frame. The CSMA/CA-VTT proved to be useful teaching aid in practice by showing sixty percent (60%) of the Regular group of twenty five (25) students that were taught using that tool, reported that they visualised the concept very high. In contrast, the Controlled group that were taught without using the tool, only four percent (4%) of students claimed that they were able to visualize the concept very high, whereas sixty eight percent (68%) of this same group regrettably lamented that their visualization to this concept was low. Such a result really suggested that the institutions especially in the sub-Saharan region did not have relevant telecommunications infrastructure that would be demonstrated before the learners. This showed that much of teaching-learning was done theoretically. It was against this background that alternative solutions of employing teaching tools like CSMA/CA-VTT were developed and used in learning institutions.

Keywords: Visualisation, collision avoidance, single medium, backoff timer (BOT), inter frame spacing (IFS), frame, CSMA/CA, CSMA/CA-VTT and heterogeneous sites.